1. Field of the Invention
The present invention relates to airbag inflation apparatuses for use in motor vehicles and, more specifically, to an airbag system for deployment in front of the knee area of an occupant.
2. Technical Background
Inflatable airbags are well accepted in their use in motor vehicles and have been attributed with preventing numerous deaths in accidents. Some statistics estimate that frontal airbags reduce the fatalities in head-on collisions by 25% among drivers using seat belts and by more than 30% among unbelted drivers. Statistics further suggest that with a combination of seat belt and airbag, serious chest injuries in frontal collisions can be reduced by 65% and serious head injuries by up to 75%. Airbag use presents clear benefits and vehicle owners are frequently willing to pay the added expense for airbags.
A modern airbag apparatus may include an electronic control unit (ECU) and one or more airbag modules. The ECU is usually installed in the middle of an automobile, between the passenger and engine compartrnent. If the vehicle has a driver bag only, the ECU may be mounted in the steering wheel. The ECU includes a sensor which continuously monitors the acceleration and deceleration of the vehicle and sends this information to a processor which processes an algorithm to determine if the vehicle is in an accident situation.
When the processor determines that there is an accident situation, the ECU transmits an electrical current to an initiator in the airbag module. The initiator triggers operation of the inflator or gas generator which, in some embodiments, uses a combination of compressed gas and solid fuel. The inflator inflates a textile airbag to impact a passenger and prevent injury to the passenger. In some airbag apparatuses, the airbag may be fully inflated within 50 thousandths of a second and deflated within two tenths of a second.
An airbag cover covers a compartment containing the airbag module and may reside on a steering wheel, dashboard, vehicle door, or vehicle wall. The airbag cover is typically made of a rigid plastic and may be forced opened by the pressure from the deploying airbag. In deploying the airbag, it is preferable to retain the airbag cover to prevent the airbag cover from flying loose in the passenger compartment. If the airbag cover freely moves into the passenger compartment, it may injure a passenger.
Airbag apparatuses have been primarily designed for deployment in front of the torso of an occupant. More specifically, airbags are disposed for deployment between the upper torso of an occupant and the windshield and instrument panel. During a front end collision, there is a tendency for an occupant, particularly one who is not properly restrained by a seat belt, to slide forward along the seat and xe2x80x9csubmarinexe2x80x9d under the airbag (hereinafter referenced as the xe2x80x9cprimary airbagxe2x80x9d).
In order to prevent such an occurrence, a knee airbag system has been developed to engage an occupant""s knees or lower legs and prevent submarining under the primary airbag. The knee airbag system includes a knee airbag which deploys during an accident to restrain forward movement of an occupant""s knees and legs. The knee airbag system may also include a fixed panel, referred to as a knee bolster panel, which is disposed in front of a knee airbag. The knee bolster panel provides a more rigid surface area than an airbag alone to better engage the knees or lower legs of an occupant to thereby restrain the occupant""s lower body. Nevertheless, the knee bolster panel does provide for some degree of deformation to minimize the impact to an occupant.
Knee airbag systems are located in the lower portion of an instrument panel. This location may interfere with the disposition of certain other members such as parking brake handles, switches, vents, speakers and other manual controls or instruments. In order to accommodate panel members, the perimeter of an knee airbag system may be xe2x80x9ctrimmedxe2x80x9d to circumvent the members. Such configuration of the system may work for members that may be disposed adjacent the exterior of the system. However, this configuration does not work well for members that are located directly within the region occupied by the knee airbag system.
In order to install a knee airbag system, the members may need to be relocated or eliminated from the region to be occupied by the system. This may prove to be extremely difficult if an automobile is to be retrofitted with the knee airbag system.
It would therefore be an advancement in the art to provide a knee airbag system which could better accommodate a member disposed in a region to be occupied by the system. It would be a further advancement in the art to provide a knee airbag system suitable for retrofitting an automobile. Such a device disclosed and claimed herein.
The present invention is a knee airbag system that may be disposed in the lower portion of an instrument panel and allows passage of one or more members through the system. The knee airbag system may include a housing for containing components of the system and may be secured to the instrument panel or to a firewall. The housing may be configured with a housing aperture to allow a protruding member to extend through. The system includes an inflator stored within the housing and operational in an accident situation. The system further includes an inflatable airbag stored within the housing and in communication with the inflator. The airbag has an airbag aperture in-line with the housing aperture. The airbag is sealed around the perimeter of the airbag aperture to enable inflation of the airbag. A bolster panel is secured to the airbag and includes a bolster aperture that is in-line with the housing aperture and the airbag aperture.
The apertures of the housing, airbag, and bolster panel define a clearance tunnel to allow passage of a protruding member, such as a manual control or instrument that is disposed within the region occupied by the system. The clearance tunnel is sufficiently sized to allow access to the protruding member and to not obstruct inflation of the airbag. The present invention may further incorporate a plurality of clearance tunnels where multiple protruding members are required. The knee airbag system is economical to manufacture and may be configured for retrofitting existing instrument panel designs.
These and other features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.